1. Field of the Invention
The invention relates to a pyrogenic zinc oxide-comprising composite of layers and to a field-effect transistor comprising this composite. The invention further relates to processes for producing the composite.
2. Discussion of the Background
The use of zinc oxide (ZnO) as a semiconductor material in field-effect transistors is described in the literature. For instance, it has been known for some time that layers deposited from the gas phase, for example via CVD, PE-CVD or atom beam epitaxy, have remarkable properties in field-effect transistors.
A disadvantage in these processes is the necessity of costly vacuum systems, which prevents their use in the field of printed electronics.
Also known in this connection is the use of colloidal systems with different particle morphologies. The layers thus produced form the so-called channel, in which, by applying a voltage at the so-called gate, charge carriers are induced, which are required for the transport of current in the switched-on state.
A disadvantage of these systems is that the zinc oxide layers have to be heat-treated at high aftertreatment temperatures in order to achieve a sufficient field-effect mobility (μFET). The temperatures are typically in the region of at least 200° C., in many cases even higher than 300° C.